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Discussion Starter · #1 ·
HI there new to the forum. Need some good answers not just a vacuum leak. Going to put all details on here. To eliminate generic answers.

97 Prelude Manual bone stock.
My problems I could say started about 3 weeks ago. After brother burrowed the car filled the car with unleaded not premium gas. had a 400 mile round trip. It was having some trouble starting then working up to losing power on the highway. In that moment on highway speeds RPM and speed drop then gets power again. As he got closer to my house. When coming to stop light or stop sign it would die immediately. After it dies you can start back up and go where you needed but have to flutter the gas to keep it alive. You can try to gently lay the RPM back down idle and would be fine.

Now i have replaced the filter and fuel pump. can hear it prime and get energized.
I have replaced the EGR valve and cleaned the ports at EGR valve only. Not intake. Seems like it go worst.
I have taken the IACV and fast idle valve off and cleaned them both. reset the idle throttle back to flush. as well.
No air in the system i believe bleed the air off right. i open the bleed valve for the coolant and no coolant comes out when engine is hot or running. not sure that is my issue there?
The EGR ports were bad full of carbon so i am sure the EGR ports are plugged with carbon.
I managed to get my hands on last EGR ports caps on earth.
replaced the spark plugs
idles around 700
750 when radiator on.
engine does not knock at all after the trip.
did put a OBD2 on and i get p0401 code

Very frustrated now and have no idea where to look. Thank you for your time and attention on helping me getting my prelude running again.
 

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700 is low for an idle setting, ideally you want closer to 800-850RPM. When you say you "reset the idle throttle back to flush", what do you mean? If it ran before, there should be no reason to adjust the idle air screw or throttle stop.

P0401 is insufficient EGR flow; odds are your intake manifold EGR ports are clogged and need to be cleaned. Still, that shouldn't cause your idle issue.
 

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Discussion Starter · #3 ·
700 is low for an idle setting, ideally you want closer to 800-850RPM. When you say you "reset the idle throttle back to flush", what do you mean? If it ran before, there should be no reason to adjust the idle air screw or throttle stop.

P0401 is insufficient EGR flow; odds are your intake manifold EGR ports are clogged and need to be cleaned. Still, that shouldn't cause your idle issue.
I have repair manual that has 750 plus or minus 50 for normal idle. And I mean the the little plastic piece in the fast idle valve you can turn back in with a crew driver. I put that back down snug.
 
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